HTTP ERROR 500 / WHMCS Fresh installation

Hello, I'm getting HTTP Error 500 with WHMCS fresh installation on OLS.

It worked normally with Apache.

IonCube loader is installed and working normally, every page works normally just WHMCS don't, every page of WHMCS getting HTTP Error 500.

phpinfo shows that IonCube is loaded and running, nothing in error logs.

Did someone had same problem maybe?

Thanks to all in advance.